Training an existing model isn’t something that’s possible with Retrobatch. However, you can make your own models with some open source tools like Turi Create: https://github.com/apple/turicreate

When MacOS Mojave 10.14 is released this fall, there will be new things in there for Retrobatch to take advantage of for making your own classifications. I don’t know exactly when I’ll add those to Retrobatch, but I hope it’s sooner rather than later.